Can I upgrade and then return to the old ios?

Question

iOS

Hello.
I've been using the device for a while now.
My iphone4s ios7.1.2
offers to update to 9.3.5 I want to update
, only so that I can go back (if something goes wrong :)).
Is that possible?
Who did what?
What instructions?
One reason some apps only come with ios8.
not updated before.
Thanks for the advice!
ps option to buy a new device do not offer!)))

Answer 1

cunning
put jail
then through OTA roll back to 6.1.3
sell on Avito for 40k
buy 6
PROFIT

Answer 2

Without a jailbreak in any way
Everyone advises not to update iOS above the 7th version on the 4 (s)th iPhone - everything starts to load and dull for a long time.
Like iOS 10, you should not bet on 5.